1. Field of the Invention
The present invention relates to an ink cartridge for storing ink for use in inkjet recording, to an inkjet recording system comprising an ink jet recording apparatus connected to an ink cartridge and to an ink jet recording apparatus. Preferably the ink jet cartridge is detachably attached to the ink jet recording apparatus which is equipped with a connection member making it possible to supply ink to the ink cartridge through application of pneumatic pressure.
2. Description of the Related Art
Ink jet recording apparatuses are available as a variety of products ranging from ones for consumer use involving printing in a relatively small amount to ones for office or commercial use allowing printing in a relatively large amount.
Of these, ink jet recording apparatuses for printing in a large amount employ a large-volume ink cartridge for a reduction in the replacement frequency of the ink cartridge. An ink cartridge of this type adopts a construction suited to be installed within a recording apparatus. And, in such a recording apparatus, ink is supplied through connection between the ink cartridge and a recording head (or a sub tank connected to the recording head) via an ink supply tube.
Further, in an inkjet recording apparatus for office or commercial use intended for printing in a large amount, an improvement of printing speed is required.
In an ink jet recording apparatus using an ink supply tube, a significant pressure loss in the supply tube may occur, so that, to supply ink in a stable manner, it is advantageous to provide a construction which helps reduce the pressure loss. In a construction achieving an improvement in terms of printing speed, pressure is applied to the ink stored in, for example, an ink cartridge, to forcibly generate an ink flow toward the recording head, thereby supplying a sub tank with ink in a necessary and sufficient amount. As an example of a system for generating pressure, a system is known in which an ink cartridge is attached to an ink jet recording apparatus in an airtight configuration and pressurized air is applied to the ink cartridge.
A configuration is generally known in which a structure related to ink supply and a structure related to pressurization are individually provided and in which they are independently connected to an ink cartridge.
In contrast, Japanese Patent Application Laid-Open No. 2004-306496 proposes a construction which is integrally equipped with a structure for ink supply and a structure for pressurization.
In the following, the construction as discussed in Japanese Patent Application Laid-Open No. 2004-306496 will be briefly described with reference to a drawing. As illustrated in FIG. 11, an ink jet recording apparatus 110 is equipped with a recording head 112 mounted on a carriage 111, and a sub tank 113 retaining ink supplied from an ink cartridge 150 described below. Further, there is provided an attachment portion 117, to which the ink cartridge 150 is detachably attached. Further, in the attachment portion 117, a connection member 120 is arranged that is connected to an ink supply member of the ink cartridge 150 when the ink cartridge 150 is attached. The connection member 120 is equipped with an ink outlet path 125, an ink outlet port (not illustrated), an air inlet path 122, and an air inlet port 121. And, the connection member 120 is connected to an ink tube 116 constituting an ink path for ink supply through connection to the sub tank 113 of the recording head 112. Further, via the air inlet path 122, the air inlet port 121 is connected to an air tube 115 constituting an air path connected to an air pump 114, which generates pressurized air for sending ink with pressure from the ink cartridge 150 to the sub tank 113.
And, an air seal 171 is provided so as to surround the ink outlet 125, the air inlet path 122, and the air inlet port 121. The air seal 171 is equipped with a lip-like peripheral edge formed of an elastic material and configured to be brought into intimate contact with the periphery of an opening 153 of the ink cartridge 150 to seal the inner space thereof when the ink cartridge 150 and the connection member 120 are connected to each other.
As illustrated in FIG. 12, the ink cartridge 150 for attachment to the ink jet recording apparatus 110 as described above includes a casing 151, which contains an ink accommodation body unit 160 composed of a spout 162 and an ink accommodation body 161. The ink accommodation body 161 consists of an ink bag formed of a flexible film. On the other hand, the spout 162 is equipped with an ink seal 163 consisting of an elastic member equipped with an ink supply port 167 which is connected to a needle-like pipe constituting the ink outlet path 125 of the connection member 120 of the ink jet recording apparatus 110. The ink accommodation body unit 160 is mounted on a regulation member 155 of the casing 151 by utilizing a part of the spout and with a play (clearance gap) between the spout 162 and the regulation member 155. Further, the casing 151 is equipped with an opening 153 configured to expose the ink supply port 167, with the ink accommodation body unit 160 arranged in the casing 151. A space portion 154 of the ink cartridge 150 communicates with the exterior via the opening 153 and the clearance gap between the regulation member 155 and the spout 162.
FIG. 13 illustrates the ink cartridge 150 illustrated in FIG. 12 as attached to the ink jet recording apparatus 110 illustrated in FIG. 11. The ink outlet path 125 is inserted through the ink supply port 167 of the ink cartridge 150 to communicate with ink 140 stored in the ink accommodation body 161 of the ink accommodation body unit 160. At the same time, the air seal 171 is pressed against and held in contact with the periphery of the opening 153 to thereby block the opening 153, with the abutment portion (lip portion) 171a of the air seal 171 being deformed. As a result, the space portion 154 formed by the inner space of the ink cartridge 150 is enclosed except that it communicates with the air inlet port 121. In this state, the air pump 114 is operated to send air in, whereby the interior of the ink cartridge 150 is pressurized to thereby compress the ink accommodation body 161, thereby sending the ink 140 to the sub tank 113 of the recording head 112 under pressure.
However, in the construction in which the air seal 171 is provided in the ink jet recording apparatus 110, when the number of times that the ink cartridge 150 is replaced increases, the material of the air seal 171 deteriorates in characteristics, making it difficult to form the airtight construction for executing the pressurized ink supply. More specifically, in the construction as discussed in Japanese Patent Application Laid-Open No. 2004-306496, the air seal 171 suffers a great elastic deformation, showing creeping with the passage of time. In this case, the pressurization force can escape to the exterior from the lip portion 171a. To prevent the escape of the pressurization force, the air seal 171 is required to retain durability during the service life of the recording apparatus, which means there are limitations in terms of material selection, configuration for securing sealing property, etc.
Further, the ink cartridge 150 is inserted, with the air seal 171 and the opening 153 of the ink cartridge 150 facing each other. Thus, the attachment is completed by causing the ink cartridge 150 to abut the lip portion 171a, so that the degree of conformity to the attachment stroke of the ink cartridge 150 is rather low (so the ink cartridge may need to be inserted several times before the ink cartridge properly abuts the lip portion 171a). To increase the degree of conformity to the stroke, it might be possible to operate the seal structure as a whole or to increase the size of the seal; which, however, would involve an increase in cost attributable to the complicated structure or a reduction in the degree of freedom in design configuration.
Further, in the construction as discussed in Japanese Patent Application Laid-Open No. 2004-306496, at the time of pressurization with air, the pressure is exerted so as to outwardly expand the lip portion 171a of the air seal 171. Thus, there is a possibility that the lip portion 171a formed of an elastic material gives way under the pressure and is detached from the casing, allowing the pressurization force to escape.
Further, the opening 153 of the ink cartridge 150 is (wide) open, and the ink supply port 167 faces the opening 153 in close proximity thereof (so the ink supply port 167 is not covered). As a result, the user is not prevented from touching the ink supply port 167, so that there is a possibility that the user gets ink on his hand while handling (e.g. attaching or detaching) the ink cartridge 150.